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In most of the world, the FM broadcast band, used for broadcasting FM radio stations, goes from 87.5~108.0 MHz. In the Americas ( ITU region 2) it starts at 88.0, at the top end of TV channel 6. In Japan the FM broadcast band is 76~90 MHz, unlike any other country in the world. The old OIRT band in Eastern Europe was 66~74MHz.The name "FM band" is usually used but is slightly misleading, as one can transmit FM on any frequency. All of these bands mentioned are in the VHF band.
1.1 Center frequencies
While most countries use frequencies ending in .1, .3, .5, .7, or .9, some use .0, .2, .4, .6, and .8. Still others use .15, .35, .55, .75, .95, or .05, .25, .45, .65, .85 instead. This offset helps to prevent co-channel interference, and take advantage of FM's capture effect and receiverThe word receiver has a number of different meanings: In communications and information processing, a receiver is the recipient ( observer) of a message ( information), which is sent from a source ( object). Receivers decode messages. A receiver (radio) i selectivityThe word selectivity has more meanings: #Selectivity # Electronic selectivity..
1.2 Channel numbering
In North AmericaNorth America is the third largest continent in area and the fourth ranked in population. It is bounded on the north by the Arctic Ocean, on the east by the North Atlantic Ocean, on the south by the Caribbean Sea, and on the west by the North Pacific Ocea, each channel is numbered from 201 (88.1 MHz) to 300 (107.9 MHz) in increments of 1 (0.2 MHz). 87.9 MHz is technically part of TV channel 6 (82.0~88.0 MHz), but is used by two class DThis is the list of broadcast station classes . Domestic classes are listed as subitems under international ones. Effective radiated power (ERP) and height above average terrain (HAAT) are listed unless otherwise noted. North America The United States, Ca LPFM stations in the U.S. as channel 200. PortablePortable communications devices refer to hand-held or wearable devices. For example, the Walkie Talkie is a device that is hand-held when in use, and wearable when not in use. Most walkie talkies have a belt clip or a housing, such as a leather holder, th radio tuners generally go down to 87.5, in case they are taken abroad. Automobiles are unlikely to go overseas, but usually tune down to 87.7, so that TV channel 6 audio on 87.75 can be received (although at a very low volume).
The basic formulas determining radio channels for North America as mentioned is as follows:
- (MHz − 47.9) * 5 = ch#
- (ch# / 5) + 47.9 = MHz
1.3 Deviation and bandpass
Normally, each channel is 200 kHz (0.2 MHz) wide, and can pass audio and subcarrier frequencies up to 100 kHz. Deviation is up to 200 kHz total, or ±100 kHz, but is typically limited to 150 kHz total (±75 kHz) in order to prevent interference to adjacent channels on the band. Stations in the U.S. may go up to 10% over this if they use stereo or other subcarriers, increasing total modulation by 1% for each 2% used by the subcarriers.
2 OIRT bandplan
